We are examining regulation of macromolecular metabolism modulated by cell architecture. Loss of this regulation seems fundamental in neoplasia. We have developed a widely used system for fractionating cells for morphological and biochemical measurements. Four fractions are produced, i.e., the soluble, cytoskeleton, chromatin and nuclear matrix. These fractions are unique in that they share very few proteins. We also have shown that protein synthesis for each fraction is regulated separately but is coordinated for all proteins in a fraction. We have discovered a prompt heat shock response which appears to be the synthesis of about 50 new proteins in the mammalian cells following exposure to 43 degrees. These proteins are entirely in the nuclear matrix and unlike the classical heat shock, appear to result from translational regulated and are from pre-existing, inactive mRNA. Morphological study of the cytoskeletal framework and the nuclear matrix-intermediate filament cell fractions permits very sensitive tests of the action of tumor promotors. All promotors examined produce a characteristic morphological signature. The same signature is produced by activated chemical carcinogens and by the presence of the mos gene product from Maloney sarcoma virus. The similar morphological and biochemical effects of complete carcinogens and promotors may explain how the two-step carcinogenesis process is accomplished by the single carcinogenic agent. We are constructing monoclonal antibody libraries for the cytoskeletal framework and for the nuclear matrix which will permit immunoelectronmicroscopy of these structures in whole mounts. We have also developed an unembedded, thick-section technique using diethylene glycol distearate which can produce embedment-free sections from 0.1 to 1 micron. These combine the advantages of sectioning with the power of visualization obtained with unembedded cell material.